The present disclosure relates to a light emitting device applicable to light sources of display devices and lamps, and to a method for manufacturing the same.
Regarding light sources of display devices and lamps, research has been conducted on light emitting devices using semiconductor light emitting elements (hereinafter referred simply to as light emitting elements) such as light emitting diodes (LEDs). Such light emitting devices using light emitting elements have been attracting attention as a novel alternative to conventional light sources such as fluorescent and incandescent lamps. In particular, LEDs are widely expected as a next-generation light source of lamps because of their long life compared to other light sources such as fluorescent and incandescent lamps and because of their light emitting capability with low energy.
Among them, white light emitting devices are expected to attract the greatest demand. One type of such devices known in the art produces white light by using a light emitting element and a phosphor to be excited by it to emit light of the complementary color. Such light emitting devices composed of a light emitting element and a phosphor are manufactured by covering the light emitting element with the phosphor layer, where the position and manufacturing method of the phosphor layer involves various techniques.
For example, for the purpose of reducing uneven color or inaccurate color as well as improving the light extraction efficiency, Patent Document 1 discloses a method of forming a phosphor layer including the steps of curing or half-curing a primary resin, thereafter putting thereon a secondary resin containing a phosphor, and sedimenting the phosphor to form a phosphor layer. In a light emitting device manufacture by such methods, its phosphor is positioned remote from its light emitting element, which is called a remote phosphor structure or technique.
The primary resin is provided for preventing the phosphor from being deposited on a conductive wire, by which the technique of Patent Document 1 is aimed at eliminating uneven color and inaccurate color.    Patent Document 1: JP 2009-94351 A
However the method disclosed in Patent Document 1 does not have a sufficient effect on uneven color, and its product suffers from possible delamination between the primary resin and the secondary resin because of the interface therebetween.
It is an object of embodiments of the present invention to provide a method for manufacturing a light emitting device that has effectively reduced uneven color and offers high reliability of being free from delamination between resins, and to provide the light emitting device.
Regarding the light emitting element of Patent Document 1, the present inventors assumed that the effect on uneven color was insufficient because there was another cause of uneven color besides the phosphor deposited on the conductive wire. Based on this idea, the present inventors intensively studied, and thus made the embodiments of the present invention.